Re: [PATCH v3 2/5] dmaengine: fsl-edma: Add FSL_EDMA_DRV_MCF flag for ColdFire eDMA

[Frank Li <Frank.li@oss.nxp.com>]

On Thu, Jun 25, 2026 at 10:59:38AM +0200, Jean-Michel Hautbois wrote:
> Add FSL_EDMA_DRV_MCF driver flag to identify MCF ColdFire eDMA
> controllers which have a native M68K register layout.
>
> The edma_writeb() function applies an XOR ^ 0x3 byte-lane adjustment for
> big-endian eDMA controllers where byte registers within a 32-bit word
> need address correction due to endianness differences between the CPU
> and hardware IP block.
>
> However, the MCF54418 eDMA is native to the ColdFire architecture and
> its 8-bit registers (SERQ, CERQ, SEEI, CEEI, CINT, CERR, SSRT, CDNE) are
> located at sequential byte addresses (0x4018-0x401F) as documented in
> the MCF54418 Reference Manual Table 19-2. No byte-lane adjustment is
> needed - applying the XOR causes writes to target incorrect registers
> (e.g., writing to CERR at 0x401D would actually access SSRT at 0x401E).
>
> Set this flag in the MCF eDMA driver to bypass the XOR adjustment and
> access registers at their documented addresses.
>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
> ---
>  drivers/dma/fsl-edma-common.h | 5 ++++-
>  drivers/dma/mcf-edma-main.c   | 2 +-
>  2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/fsl-edma-common.h b/drivers/dma/fsl-edma-common.h
> index abc8f7805515..64b537527291 100644
> --- a/drivers/dma/fsl-edma-common.h
> +++ b/drivers/dma/fsl-edma-common.h
> @@ -225,6 +225,8 @@ struct fsl_edma_desc {
>  #define FSL_EDMA_DRV_TCD64		BIT(15)
>  /* All channel ERR IRQ share one IRQ line */
>  #define FSL_EDMA_DRV_ERRIRQ_SHARE       BIT(16)
> +/* MCF eDMA: Different register layout, no XOR for byte access */
> +#define FSL_EDMA_DRV_MCF                BIT(17)
>
>
>  #define FSL_EDMA_DRV_EDMA3	(FSL_EDMA_DRV_SPLIT_REG |	\
> @@ -419,7 +421,8 @@ static inline void edma_writeb(struct fsl_edma_engine *edma,
>  			       u8 val, void __iomem *addr)
>  {
>  	/* swap the reg offset for these in big-endian mode */
> -	if (edma->big_endian)

I think native endian, needn't set big_endian. Does it work if don't
set big_endian for MCF54418?

Frank

> +	/* MCF eDMA has different register layout, no XOR needed */
> +	if (edma->big_endian && !(edma->drvdata->flags & FSL_EDMA_DRV_MCF))
>  		iowrite8(val, (void __iomem *)((unsigned long)addr ^ 0x3));
>  	else
>  		iowrite8(val, addr);
> diff --git a/drivers/dma/mcf-edma-main.c b/drivers/dma/mcf-edma-main.c
> index 9e1c6400c77b..f95114829d80 100644
> --- a/drivers/dma/mcf-edma-main.c
> +++ b/drivers/dma/mcf-edma-main.c
> @@ -145,7 +145,7 @@ static void mcf_edma_irq_free(struct platform_device *pdev,
>  }
>
>  static struct fsl_edma_drvdata mcf_data = {
> -	.flags = FSL_EDMA_DRV_EDMA64,
> +	.flags = FSL_EDMA_DRV_EDMA64 | FSL_EDMA_DRV_MCF,
>  	.setup_irq = mcf_edma_irq_init,
>  };
>
>
> --
> 2.39.5
>